Corsair Apple Certified 4GB (1x4GB) DDR3 1333 MHz (PC3 10666) Laptop Memory 1.5V Capacity: 1 x 4GB Speed: 1333MHz CL9 Timing: 9-9-9-24 (1333 MHz) Pin Out: 204 Pin Voltage: 1.5V Latency: CAS 9 Tested at Apples compatibility lab to ensure functionality with all current DDR3 based Macbook Pro, iMac, and Macbooks. Memory Type: DDR3; Speed: 1333MHz Lifetime Warranty